1. The Technical Field
The present invention relates generally to apparatus for electronic storage of data. More particularly, the present invention relates to disk drives and disk controllers for use in computers and other electronic apparatus.
2. The Prior Art
Various types of electronic data storage devices for use in connection with digital computers and the like have been developed over the years. Such devices include floppy disk drives which typically use easily removable and transportable magnetic storage media; hard disk drives which typically use fixed magnetic storage media; tape drives which typically use easily removable and transportable removable magnetic storage media; and optical disk drives, such as compact disk read-only memory (CD-ROM), compact disk read-write (CD-RW), and digital versatile disk (DVD) drives, among others, which typically use easily removable and transportable optical storage media.
A typical computer, especially a microcomputer or personal computer, often includes more than one of such data storage devices. A typical microcomputer, for example, might include an internal, fixed hard disk drive, a 3.5 inch floppy disk drive, and a CD-ROM drive. Each such device typically would be a discrete unit including its own disk controller, and the various devices typically would be independently mounted at various different locations on the computer""s chassis. Further, each such device typically would be interconnected with each of the other devices and a disk/bus interface adapter which typically would be mounted on the computer""s chassis. Ribbon cable having an inline connector for connection to each such device is commonly used for this purpose.
The foregoing architecture has certain shortcomings. For example, the ribbon cable typically used to interconnect the various data storage devices is costly and prone to damage, particularly as the number of interconnected disk drives increases. Such cable can be easily damaged by persons performing maintenance or repair activities on the computer""s chassis. Also, the connectors used in connection with such cables generally are installed at certain predetermined locations, based on the installed locations of the storage devices they are intended to connect to, and they are not readily moved from one location on the cable to another. Consequently, in order to install and connect an additional storage device in a typical personal computer, for example, an additional inline connector must be installed at the appropriate location on the ribbon cable. This procedure requires special tools and skill, and can result in damage to the cable if performed incorrectly. Further, the existing ribbon cable often will be just long enough to interconnect the existing drives in their original locations. If any or all of the existing drives are moved from their original locations to different locations, or if new drives are added, the existing ribbon cable (and its connectors) might need to be replaced in its entirety in order to permit interconnection of the drives in their new layout.
Modern hard disk drives are much less expensive and have much greater storage density than their forerunners. Further, modern disk drive technology allows for smaller, more compact drives than previously possible. In some applications, it may be desirable to use a number of smaller disk drives, rather a single, larger hard drive having the same aggregate storage capacity. For example, it may be easier to package a number of smaller units into a particular space than one larger unit. Also, if a number of smaller units is used in place of a single larger unit, a random failure of a single smaller unit is likely to result in the loss of less data than a random failure of a single larger unit. However, if an application is to include a large number of smaller devices, it becomes impractical to interconnect such units using conventional means, such as the interconnecting cabling described above. Also, because each individual, conventional disk drive typically includes its own dedicated disk controller, an installation using a large number of smaller disk drives would require allocation of a relatively large volume of space to the disk controllersxe2x80x94space that could be better used for data storage.
The present invention is directed to electronic data storage apparatus having high data accessibility, data transfer rate, fault tolerance, and redundancy, among other characteristics. The present invention allows for interconnection of any number of data storage devices with any number of computers, processors, or other electronic apparatus, with unlimited flexibility.
In a preferred embodiment, one or more data storage devices are mounted on and electrically connected to a card that can be inserted and secured into a receptacle, or slot, in the chassis of a computer or other apparatus. In a preferred embodiment, the data storage devices are miniature hard disk drives. In other embodiments, optical disk drives, flash memory modules, or other types of data storage devices may be used instead of, or in addition to, hard disk drives.
In a preferred embodiment, the card includes a printed circuit portion, and each disk drive mounted onto the card includes output pins similar to the output pins found on a conventional integrated circuit package. In one such embodiment, a disk drive""s output pins are soldered directly to the printed circuit, thus securely connecting the disk drive to the card both mechanically and electrically. The disk drive""s output pins can be bent pins which are soldered to the printed circuit on the side of the card adjacent to the disk drive, i.e., surface mounted, or they can be straight pins which extend through holes in the card and are soldered to the printed circuit on the side of the card opposite the disk drive. Surface mounting sometimes is preferable because the bent pin structure tends to provide an amount of shock absorption for the disk drive.
In an alternate embodiment, one or more multi-pin electrical connectors are soldered directly to the card and the disk drive""s output pins are inserted into corresponding pin receptacles in such connectors. In this manner, the disk drive is electrically and, to some extent, mechanically connected to the card. If additional mechanical support is required to securely fasten the disk drive to the card, it can be provided by using screws, clamps, or other devices to secure the disk drive to the card. This embodiment permits relatively simple replacement of a disk drive once the card it is mounted on has been removed from its associated apparatus because desoldering and resoldering are not required.
In another embodiment, the disk drive includes electrical contact pads instead of, or in addition to, output pins, and the card includes corresponding electrical contact pads which are integral with the printed circuit or are external to, but connected to, the printed circuit. In such an embodiment, the disk drive is placed upon the card so that the electrical contact pads on the disk drive become engaged with the corresponding electrical contact pads on the card, and the disk drive is then secured to the card using screws, clamps, or any other suitable device.
In any of the foregoing embodiments, additional disk drives or other data storage devices may be stacked upon the disk drives or other data storage devices which are mounted directly to the card.
In a preferred form, the card also includes one or more electrical connectors for electrically connecting the card and the disk drives and other circuitry thereon to the card""s associated computer or other apparatus when the card is inserted into a slot in the chassis of such a computer or apparatus. Any suitable electrical connector, conventional or custom, can be used for this purpose.
One or more disk controllers are used to control data flow to and from each of the disk drives mounted on a card. In a preferred embodiment, a card includes a single disk controller which controls the data flow to and from each of the disk drives on that card. In an alternate embodiment, a card includes more than one disk controller, each of which is associated with one or more disk drives mounted on that card or on another card. In yet another embodiment, a card has no disk controller thereon, and the data flow to and from the disk drives mounted on that card is controlled by a disk controller which is mounted on a different card or elsewhere within the associated computer or other apparatus with which the disk drives are associated.
In the foregoing embodiments, the card has been described as having a printed circuit portion to which the various disk drives and electrical connectors are electrically connected. In other embodiments, the printed circuit portion may be replaced or supplemented by discrete wires interconnecting the various components mounted on the card.
In an embodiment of the invention, a single card is associated with a single computer or other electronic apparatus, effectively coupling only the disk drives mounted on the card to only that computer in what may be referred to as a one-dimensional array. That is, a single array of disk drives mounted on a single card is associated with a single computer or other electronic apparatus. In another embodiment, more than one card is associated with a single computer or other apparatus, effectively coupling any or all of the disk drives on those cards to only that computer in what may be referred to as a two-dimensional array. That is, two or more arrays of disk drives mounted on two or more cards are associated with a single computer. In yet another embodiment, more than one card is associated with more than one computer, effectively coupling any or all of the disk drives on those cards to any or all of the connected computers in what may be referred to as a three-dimensional array. That is, two or more arrays of disks mounted on two or more cards are associated with two or more computers. In this embodiment, a switch or router is used to direct data between a selected card/disk drive and a selected computer. In further embodiments, multiple arrays of cards can be interconnected with one or more computers in the same manner that multiple arrays of disk drives can be arrayed with computers, as described above.
As illustrated by the foregoing embodiments, the present invention allows unlimited flexibility in interconnecting any number of disk drives with any number of computers, processors, or other electronic apparatus and operating such disk drives in association with such computers or other apparatus. For example, in one possible application, any number of disk drives can be used for data storage for a computer. A number of disk drives can be used for primary data storage and a number of additional disk drives can be used for real-time redundant data storage to prevent loss of data in the event a primary data storage device fails. Further, any number of data storage devices can be provided for use as spares which can be placed into immediate service to replace a failed primary or redundant data storage device. Such spares can be placed into service without taking the computer out of service or otherwise disrupting the computer""s operation by simply rerouting data destined for the failed device to the spare device. The computer can be programmed to effect such rerouting automatically upon detecting a disk drive failure.